After the resource entities have been allocated to a controlling entity (or in the case of a Batch block, a carrier entity), the controlling entity typically continues flowing through the model to represent some behavior of the system under investigation. In the simplest case, as in the previous banking system example, the controlling entity might move on to a Delay block for a period of time and then be routed to a Release block to have the resource entity. However, if you are modeling a more complicated system, such as an emergency room, it is not hard to imagine resource entities staying with a controlling entity as it flows through various parts of the model. When a patient enters an emergency room, the patient might be assigned a nurse, a doctor, and a surgery room, and then go into surgery for some time period. After the surgery, the doctor and surgery room might be released from the patient, but the nurse might stay with the patient and a recovery room might be added as a resource entity.

In a manufacturing example, parts could be modeled as resources and they could be continually added to the controlling entity as it progresses down the virtual assembly line. In this case, the controlling entity will never release the part entities since they are essentially consumed to build the final product.